Steel doesn’t have one tensile strength — it varies by grade, alloy content, and heat treatment, roughly spanning 360 MPa to over 2,000 MPa (52,000–290,000+ psi) across the full range of commercial and specialty steels. A plain structural grade like A36 sits at the low end of that range; a maraging or ultra-high-strength alloy sits at the high end. If you need a single grade’s number for a spec sheet or calculation, use the table below rather than a generic “steel is X MPa” figure — that number doesn’t exist.
Tensile Strength by Steel Grade
| Steel Type / Grade | Ultimate Tensile Strength (MPa) | UTS (psi / ksi) | Confidence |
|---|---|---|---|
| A36 structural steel | 400–550 | 58,000–80,000 | High — independently confirmed by ChatGPT, Perplexity, and Gemini at the same range |
| A992 structural steel | ≈450 | ≈65,000 | Single source — reference only |
| 1018 mild/low-carbon steel | ≈440 | ≈64,000 | Single source — reference only |
| 304 stainless steel | 505–820 | 73,000–119,000 | Two sources, ranges overlap but don’t fully agree (see note below) |
| 4140 chromoly steel, annealed | ≈655 | ≈95,000 | Single source — reference only |
| 4140 chromoly steel, quenched & tempered (QT 800) | ≈1,080 | ≈156,000 | Single source — reference only |
| A514 high-strength steel | ≈760 | ≈110,000 | Single source — reference only |
| Maraging / ultra-high-strength steel | 2,000–2,700+ | 290,000+ | Two sources agree on magnitude, differ on the exact ceiling — treat as “2,000 MPa and up” |
On the 304 stainless row: one source puts the range at 505–700 MPa, another at 515–820 MPa. The lower bounds are close (505 vs. 515); the upper bounds diverge more (700 vs. 820). Rather than picking one number to look precise, the honest range is the full span — actual tensile strength for 304 depends heavily on cold-worked vs. annealed condition, so if you’re specifying this material, get the mill certificate for your actual heat/condition rather than relying on a published range.
On everything below the A36 row: those numbers come from a single AI-sourced reference each and weren’t independently cross-checked in this research pass. They’re directionally useful (4140 in a quenched-and-tempered condition really is roughly 1.6× stronger than the same alloy annealed, which matches known heat-treatment behavior for chromoly steels), but don’t treat them as precise enough to design against without verifying against the actual mill cert or ASTM spec for your material lot.
Why the Range Is So Wide
The same base element (iron, plus up to about 2% carbon and alloying additions) can land anywhere across that 360–2,700+ MPa range depending on three things:
- Carbon and alloy content — more carbon and alloying elements (chromium, molybdenum, nickel) generally raise achievable strength, at some cost to ductility and weldability.
- Heat treatment — the same alloy in annealed vs. quenched-and-tempered condition can differ by 50% or more in tensile strength (see the two 4140 rows above — same grade, different heat treatment, ~65% strength difference).
- Processing — cold-worked (rolled, drawn) steel is stronger than the same composition in a hot-rolled or annealed state, because cold working introduces dislocations that resist further deformation.
This is why a spec sheet or PPAP report references a specific ASTM/SAE grade and condition (e.g., “4140 QT” rather than just “4140”) — the grade alone doesn’t pin down the number.
Yield Strength vs. Tensile Strength — Don’t Confuse the Two Numbers
For A36 structural steel, yield strength runs around 250–350 MPa — meaningfully lower than its 400–550 MPa tensile strength. That gap matters: yield strength is the number engineers actually design to (with a safety factor), because it’s the point where the material starts permanently deforming. Tensile strength (UTS) is where it breaks outright. A part spec’d against tensile strength alone, without accounting for the lower yield point, is at risk of permanent deformation well before it ever approaches its rated “strength.” For the full breakdown of yield vs. UTS vs. fracture point, see What Is Tensile Strength?.
Related reading: What Is Tensile Strength? · How to Calculate, Measure, and Test Tensile Strength
